Systemic and local immune responses of four cases with lower respiratory tract illness due to reinfection with respiratory syncytial virus.

Four infants and children who had tracheobronchitis or bronchiolitis by respiratory syncytial virus (RSV) reinfection were presented. Their clinical features, systemic and local immune reactions to RSV were compared with those of eleven age-matched patients who had lower respiratory tract illness with primary RSV infection. Moderate antibody activities in their nasopharyngeal secretions and sera which were comparable to those of convalescent phase of primary infection were observed within several days after onset of illness; however, their clinical symptoms, such as fever or wheezing, lasted almost as long as in primary RSV infection. These observations suggest that the higher serum and secretory antibody activity to RSV during acute phase does not always bring about clinical amelioration in RSV reinfection. The contribution of immunopathological reaction between RSV and RSV-specific antibodies might also be considered as a cause of inflammation during the acute phase of RSV reinfection.